luogu1441 砝码称重

Posted 2020-10-18 poorpool

搜索+背包就是了

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;
int n, m, a[25], ans=0, lst=0;
bool isu[25], f[2005];
void dfs(int x){
    if(x==m+1){
        int cnt=0;
        memset(f, 0, sizeof(f));
        f[0] = true;
        for(int i=1; i<=n; i++)
            if(!isu[i])
                for(int j=2000; j>=a[i]; j--)
                    f[j] |= f[j-a[i]];
        for(int i=1; i<=2000; i++)
            if(f[i])
                cnt++;
        ans = max(ans, cnt);
        return ;
    }
    for(int i=lst+1; i<=n; i++){
        isu[i] = true;
        lst = i;
        dfs(x+1);
        isu[i] = false;
    }
}
bool vis[2005];
int main(){
    cin>>n>>m;
    for(int i=1; i<=n; i++) scanf("%d", &a[i]);
    dfs(1);
    cout<<ans<<endl;
    return 0;
}